The Pará river is an estuary located in northeastern Pará. One of its main importance is the fact that this region is the port of the main ports of the state of Pará, with the Quiriri channel as a passage, which currently has depth that allows the passage of vessels up to 13.8 meters. It is speculated that these ports move more than 670 million of reais every year. The methods of measuring the tide are diverse, one of the most used being the application of float-type tide gauges. However, methodologies have made great progress in this area. Currently the dual frequency GPS or DGPS (Differential Global Positioning System) has high accuracy because its measurements are based on two satellite constellations, the Global Positioning System (GPS) / Global Navigation Satellite System (GLONASS) networks, together with an antenna installed on land (RTG System - Real Time Gipsy). Thus, this equipment proves to be able to measure the tide by varying the ellipsoidal altitude. With this in mind, the aim of this paper is to analyze and compare the accuracy and precision of the DGPS screening mareograph method in relation to the buoy-counterweight digital tide gauge in a tropical estuarine system of the Amazon region, in two situations, the first one where the equipment was distant from each other and the second in which they were close. Tide graphs, linear regressions and coherence wavelets were produced in order to analyze the correlation between the two tidal methods. The results of linear regressions and coherence wavelets showed a strong correlation and coherence between the two methods. It was observed that the smaller the distance between the collected data, the greater correlation between the tidal data. Thus, the method of obtaining tides through the difference in ellipsoidal altitude of the DGPS screenings was found to be efficient when compared to the digital buoy-counterweight tide gauge. It is noteworthy that DGPS handwriting is a high cost method when compared to the digital tide gauge, because of this, it is indicated for those aiming to get the local tide and already have the equipment and a vessel.
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